]]>http://www.mathisfunforum.com/profile.php?id=20032006-03-15T21:39:05Zhttp://www.mathisfunforum.com/viewtopic.php?pid=31492#p31492Your equation for the gradient of the radius is correct. Note that it doesn't matter if you take p - c or c - p as long as you are consistent (sign switches in both numerator and denominator and thus cancels).]]>http://www.mathisfunforum.com/profile.php?id=32032006-03-14T17:56:43Zhttp://www.mathisfunforum.com/viewtopic.php?pid=31362#p31362x² + y² = 8 at (2, 2)(2)² + (2)² - 8 = 0 (satisfy that the point lies on the circle)

x² + y² = 8(x + 0)² + (y + 0)² = 8center point is (0, 0).

0 - 2/0 - 2 = -2 / -2 = 1the gradient of the radius is 1 and thus the gradient of the tangent is -1.

y - 2 = -1(x - 2) --> y = x + 4.

]]>http://www.mathisfunforum.com/profile.php?id=20032006-03-14T14:39:51Zhttp://www.mathisfunforum.com/viewtopic.php?pid=31350#p31350I need to find the equations of tangents on circles at certain points.I have the co-ords of the point(p) and the co-ords of the center(c). To work out the gradient of the radius from the center to the point I do:y(c) - y(p) / x(c) - x(p)Is this correct or should I take (p) - (c) instead?]]>http://www.mathisfunforum.com/profile.php?id=20032006-03-14T14:35:23Zhttp://www.mathisfunforum.com/viewtopic.php?pid=31349#p31349